Disposable absorbent articles are broadly available and consumers are used to a high performance for the collecting and retaining of menses (in the case of sanitary napkins or panty liners) or for the collecting and retaining urine and fecal material (in the case of e.g. disposable diapers). From such articles consumers expect a superior absorbency behavior and at the same time expect excellent the wearing comfort and the dryness when being worn.
Often, such articles comprise multiple absorbent members, at least one member being primarily designed to store liquid, and at least one other member primarily designed to acquire and/or distribute liquid, the members typically being encapsulated between a topsheet (on the wearer facing side) and a backsheet (on the garment facing side).
In modern absorbent articles the absorbent core will typically comprise a superabsorbent material in combination with a fibrous material, for example cellulose. In particular, the storage layer will be provided from a combination of such materials. It is important to maintain the integrity of such absorbent core, both when the article is dry and when the article is wet, that means before use and in use. It is also important to prevent the escape of any of the absorbent materials providing the core, in particular the escape of super-absorbent materials, which are often provided in the form of particles. The escape of super-absorbent materials from the core could ultimately lead to contact of such superabsorbent materials with the skin of the wearer. This phenomenon is known as gel on skin (as the super-absorbent materials are often also referred to as hydrogels). However, such gel on skin occurrences are considered undesirable as many consumers consider the skin contact of such super-absorbent material to be unpleasant. Some recent absorbent articles, especially disposable diapers, employ relatively open topsheet structures. These open topsheets promote the absorbance or at least the adherence of high viscosity exudates, such as bowel movement. However, when it's specifically comes to gel on skin problems, these open topsheet structures present a challenge, as they do not represent a highly effected barrier for super-absorbent particles, which may escape from the absorbent core of the absorbent article.
U.S. Pat. No. 4,573,986 (filed in 1984) discloses an early attempt for obviating lifting out of fibers and particulate matters from the absorbent core of an absorbent garment. A wet-strength-tissue envelope is disclosed in which the absorbent core is disposed and secured. The wet-strength-tissue paper or a similar laminate is secured in face to face relation with the core by an open pattern of adhesive, which may, for example, comprise a fine pattern of globulettes of adhesive. Alternatively, a reticulated network of filaments of adhesives can be used.
EP 847 263 (filed in 1995) discloses a more recent core wrap material: Disclosed is a core wrap made from a fibrous non-woven web, preferably a polypropylene meltblown non-woven material. This core wrap material may be folded over on itself and then sealed using, for example, adhesives, heat and/or pressure. In this context, ultrasonic bonder, thermo-mechanically bonding means and adhesives are specifically disclosed as suitable sealing means.
EP 1 088 537 (filed in 2000) discloses a highly water absorbent sheet. This absorbent sheet comprises fine cellulose fibers which provide a fibrous network holding solid super-absorbent particles in position. In order to prevent the escaping of such superabsorbent particles, the disclosed absorbent sheet relies on a hot-melt adhesive forming a further fibrous network and covering the super-absorbent particles.
WO 00/64396 (filed in 2000) discloses yet a further approach for integrity and immobilization enhancement for an absorbent member. The method comprises the application of a foamable movement obstruction agent to an absorbent member.
As to provide the desired absorbency to the article, at least the storage member will typically comprise super-absorbent material, which is admixed with the traditionally used pulp fiber material. Such super-absorbent materials can absorb many times (e.g. 10, or 30 times) their own weight and are therefore very helpful when designing an article of improved fluid handling properties. Many recent products employ higher and higher concentrations of super-absorbent materials, that is concentrations in excess of 50% of the total weight of the storage member. These products achieve a high absorbing capacity with a very thin storage member and are thereby typically overall thin products. While super-absorbent materials can store very large amounts of liquid, they are often not able to distribute the liquid from the point of impact to more remote areas of the absorbent article and to acquire the liquid as fast as it may be received by the article.
Hence, the prior art has disclosed various attempts to prevent the escaping of super-absorbent particles from the absorbent core. However, especially when it comes to absorbent cores with high concentrations of super-absorbent material and the use of relatively open topsheet structures, an even more efficient prevention of the escaping of super-absorbent particles from the absorbent core is desirable.